FIG. 1 is a structural diagram showing one pixel of a liquid crystal display (LCD) panel. As shown on FIG. 1, a drain of a thin film transistor is connected with a data line 11, a gate is connected with a scan line 12, and a terminal of a source is connected with a pixel electrode, and another terminal is connected with a storage capacitor Cst. Another terminal of the storage capacitor Cst is connected with a common electrode. The voltage of the common electrode is designated VCOM. For an IPS or FFS mode, VCOM is located at an array substrate. For a VA or TN mode, VCOM is located at a color filter substrate. A deflection angle of liquid crystal molecules is determined by a voltage difference of a pixel electrode and a common electrode, and brightness (gray-scale value) of the pixel is thus determined.
In general, the common electrode is applied with a direct current (DC) or alternating current (AC) driving, and usually the direct current will be driving. A direct current potential of the common electrode is obtained by rectifying the alternating current, so this would inevitably lead to the presence of an amount of alternating current which is not filtered out. In addition, a wave of a direct current signal is generated caused by a load variation driven by the potential or environment (charging or electromagnetic interference), and the slight wave is called a ripple.
FIG. 2 is a diagram showing an output section of a common voltage generating module. There will usually be outputted through a voltage follower, which is used for performing a buffered isolation. A common voltage is inputted into an anode input terminal of the voltage follower 14. A output terminal of the voltage follower 14 is grounded through a resistance R and a capacitor C so as to remove the alternating current. A processed common voltage 15 is connected to another terminal of the storage capacitor Cst. The outputted waveform generally comprises an alternating ripple. For VCOM, the ripple will be changed over time, so the voltage for applying to the pixel will be changed. Thus, when a frame is displayed by the LCD, the pixel voltage at two adjacent rows will different, thereby producing a crosstalk phenomenon.
Accordingly, it is necessary to provide a voltage regulation circuit to solve the technical problem in the prior art.